The genome structure of several baculoviruses will be studied by use of restruction endonuclease enzymes, DNA-DNA hybridization to assess the degree and nature of conserved sequences among baculovirus DNAs, and physical mapping of ordered restruction enzyme fragments. Since physical maps are available for Autographa californica NPV and several cloned variants, transcription and translation in a susceptible cell line will be studied in order to elucidate the functional organization and expression of viral activities. These studies will be extended to non-permissive cells in order to evaluate baculovirus persistence and expression. This will aid in the assessment of the limits of baculovirus specificity relative to their use as a virological pesticides. Baculoviruses with distinct phenotypic and genetic markers will be investigated for recombination and mutation. These tools will rapidly advance our understanding of baculovirus molecular biology in invertebrate cells, and develop the information needed for investigating potential use of baculovirus genomes as cloning vectors in the invertebrate encaryotic cell.